The present invention generally relates to apparatus and methods for fireproofing and, more specifically, to apparatus and methods of providing a monolithic composite firewall in the canted deck of an aircraft.
Temperature and safety considerations bring out the need for fireproofing in a variety of applications. For example, the canted deck of the V-22 Osprey aircraft has a fire protection requirement for the cabin roof below the mid-wing area below the auxiliary power unit (APU).
Referring to FIG. 3, there is shown a conventional configuration of the graphite panel from which the V-22 canted deck is constructed. Graphite panel 130 may be made of a plurality of graphite plies 140. Each graphite ply 140 may be bonded with an adjacent graphite ply 140 by any conventional means such as a commercially available resin. Preferably, graphite panel 130 contains from 4 to 12 graphite plies 140. More preferably, graphite panel 130 contains from 6 to 10 graphite plies 140.
Referring to FIGS. 1-2, there is shown a conventional means for providing fire protection in an aircraft canted deck. Fire protection for the V-22 canted deck 100 utilizes 0.012 in thick titanium panels 110 which are mechanically fastened and bonded to the V-22's canted deck 100. Titanium panels 110 are bonded at bond area 120 to the graphite panel 130 which makes up the canted deck 100. Mechanical fasteners pass through holes 122 in titanium panel 110 for mechanically securing graphite panel 130 to titanium panel 110. The titanium panels 110 require secondary bonding in addition to mechanical fastening in order to be secured to the graphite laminate 130 of the canted deck 100. Over time, the bond line between the titanium panels 110 and the canted deck 100 becomes susceptible to dis-bonding, thus allowing fluids to migrate between these two surfaces. This creates a potential safety issue as the integrity of the firewall is reduced.
Conventional titanium panel firewalls have the further disadvantage of increased fabrication complexity and manufacturing flow time. Under current procedure, the titanium panels are manufactured and located on the canted deck. Pilot holes are drilled through the panels and the canted deck skin. These holes are opened to full size and the panel is disassembled. After cleaning/deburring/abrading the entrance and exit holes in the panel and canted deck skin, the panel is reassembled and bonded to the canted deck. Finally, mechanical fasteners are applied through the previously drilled holes to secure the titanium panel firewall to the canted deck. In addition, the manufacture of titanium panel firewalls is made even more difficult when the parts are highly contoured.
Conventional titanium panel firewalls have the additional disadvantage of high cost and weight. Providing adequate firewall protection within a defined cost/weight parameter is an important consideration. Precision aircraft, such as the V-22 Osprey, have specific specifications with respect to firewall durability and overall weight.
As can be seen, there is a need for an improved apparatus and method that provides an effective, durable, weight proportionate firewall without the need for secondary bonding, mechanical fasteners or complex manufacturing steps.